Multi-mode and multi-pitch conveyor system

ABSTRACT

A conveyor system comprising: a track section comprising a control system; a drive system that is controlled by the control system; a plurality of moving elements that are driven by the drive system; a pallet support apparatus; a plurality of pallets that are configured to engage with the moving elements and move on the pallet support apparatus; and a plurality of workstations provided along the track section, each workstation at a predetermined pitch from each other workstation, wherein at least some of the pitches are different among workstations, wherein the control system, drive system and moving elements are configured such that each pallet of the plurality of pallets is independently advanced through the workstations based on the pitches of the workstations.

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 61/202,475 filed Mar. 3, 2009, which isincorporated herein by reference in its entirety.

FIELD

This application generally relates to conveyor systems and methods, andmore specifically to modular conveyor systems and methods that provideintegration with conventional conveyor systems and multiple movingelements under independent control that allow for multiple pitchmovement of pallets.

BACKGROUND

There are a number of fundamental limitations with conventionalmechanical conveyor systems such as those which employ a belt fortransporting pallets between processing stations. First, the speed ofthe belt is typically quite limited. This is largely due to the factthat the pallets are typically stopped by mechanical stop mechanisms,e.g., in order to be processed at a processing station. Thus, if thebelt conveyor is operated at a high speed, the strong impact between apallet and mechanical stop is likely to jar whatever parts the palletmay be carrying for processing. Second, it is generally not possible tovary the acceleration and velocity profiles for individual pallets. Forinstance, if a first pallet is empty and a second pallet is loaded withdelicate parts, it is generally not possible to aggressively acceleratethe first pallet to a high speed while controlling the second palletusing more gentle acceleration and a differing velocity profile. Thislimitation may affect the latency and the throughput of themanufacturing line because empty pallets will generally have to flowthrough at the same rate as the loaded pallets. Third, a belt conveyoris typically not bidirectional, which may result in a suboptimal designof the manufacturing line. Fourth, the belt conveyor typically provideslimited flexibility or programmability, such as being able to havemultiple stopping locations at one processing station or being able tovery quickly change the positions of processing stations when the lineis adjusted/changed. Finally, the data acquisition capabilities providedby the belt conveyor are typically quite limited. For example, it istypically not possible to know where the pallets and their constituentloads are located along the conveyor at all times. Thus, for instance,it may be difficult to know how many pallets are queued at a particularprocessing station.

Conventional conveyor systems making use of scroll cams are also knownbut have some limitations as well. For example, scroll cam systems mayhave or develop reduced postional repeatability due to existing ordeveloped play in the cam grooves. Scroll cam systems also havegenerally no or very limited flexibility or programmability.

For these and other reasons, a conveyor system having multiple movingelements or pallets under substantially independent control may bedesirable for various types of applications.

Conveyor systems having multiple pallets under substantially independentcontrol are known in the art, but suffer from a variety of limitations.For example, in some cases involving linear motors, the carts or palletscannot be positioned to stop at any point along the conveyor, but onlywhere linear motors are disposed. This makes changing the location of astation a troublesome endeavour. In addition, it is difficult topinpoint the location of a moving pallet at any time.

In another conventional system involving a moving-magnet type lineard.c. brushless motor having plural moving elements disposed for motionalong a track, the fact that a separate track of position/commutationsensors is required for each moving element means that the system canonly accommodate a relatively small number of moving elements. Second,the length of the linear motor is limited by a servo-control mechanism,described as a single microcomputer, which can only process andaccommodate a limited number of the position/commutation sensors andassociated electric current generating control circuitry. Third, thewinding arrangement of the stator armature is essentially that of alinear stepper motor, which presents an uneven magnetic reluctance alongthe stator armature resulting in relatively noticeable cogging effectsand a jerky thrust production. Finally, the, coreless design of thestator armature also results in a relatively low average thrustproduction which may not be suitable for typical conveyor systemapplications.

Some conventional conveyor systems that have independent control havedrawbacks with regard to space limitations and/or material requirements.For example, some magnetic oriented conveyors are not able to bypassrejects or empty pallets or bypass an unload station when a reject orempty pallet is discovered. Some conventional conveyor systems require alarger footprint because of requirements that an entire loop beavailable for pallet movement or extra modules are needed for partloading/unloading stations.

While independently controlled conveyor systems can have variousbenefits, cost concerns will often dictate a need for lower pricedconventional mechanical conveyors, depending on the conveyingapplication involved.

SUMMARY

Accordingly, there is a need for improved apparatuses, systems andmethods for conveying which allow for multi-mode conveying, multi-pitchmovement of materials, and improved mechanical conveyors.

According to one aspect herein, there is provided a conveyor systemcomprising: a track section comprising a control system; a drive systemthat is controlled by the control system; a plurality of moving elementsthat are driven by the drive system; a pallet support apparatus; aplurality of pallets that are configured to engage with the movingelements and move on the pallet support apparatus; and a plurality ofworkstations provided along the track section, each workstation at apredetermined pitch from each other workstation, wherein at least someof the pitches are different among workstations, wherein the controlsystem, drive system and moving elements are configured such that eachpallet of the plurality of pallets is independently advanced through theworkstations based on the pitches of the workstations.

In a particular case, each workstation may have a predetermined cycletime and at least some of the cycle times may be different amongworkstations and wherein the control system, drive system and movingelements may be configured such that each pallet of the plurality ofpallets is independently advanced through the workstations based on thecycle times of the workstations.

In a particular case, the drive system may comprise a magnetic drivesystem and each moving element may comprise a magnetic conductor.

In another particular case, each workstation may be provided with aworkstation locking mechanism that is configured to lock a pallet inposition at the workstation for the cycle time. In this case, theworkstation locking mechanism may first lock the pallet in positionprior to releasing engagement with the moving element and allowengagement of the moving element prior to releasing the pallet.

In still another case, an upper runner and a lower runner may supportthe moving elements on the track section. The upper runner may be angledto provide pressure holding the moving elements between the upper runnerand the lower runner.

In some cases, the workstations comprise workstations with multiplepallet locations to operate on more than one pallet at a time in orderto adjust for differing cycle times.

In some cases, the control system comprises a moving element trackingsystem comprising: an encoder strip provided to the moving element; aplurality of encoder read heads provided to the track section andconfigured to read the encoder strip as moving elements move past thelocation of the encoder read heads. In this case, the encoder stripcomprises a plurality of index points staggered along the strip.

According to another aspect, there is provided a conveyor systemcomprising: an infeed station comprising: a singulator provided to holdpallets received from an infeed conveyor and release them singly fromthe infeed section; a track section in communication with the infeedstation, the track section comprising: a plurality of moving elementsconfigured to engage with pallets from the infeed section; a track; aworkstation; a control system configured to independently control themoving elements for movement along the track to and from theworkstation; and an outfeed station configured to receive pallets fromthe track section and feed the pallets to an outfeed conveyor, which isin communication with the track section, for additional processing.

In some cases, the track comprises a magnetic drive system.

In some cases, the moving elements the moving elements engage anddisengage with the pallets via an engagement system comprising: a movingelement portion that is biased to be engaged but can be disengaged at aworkstation; and a workstation portion provided at the workstation andconfigured such that, when the moving element enters the workstation theworkstation element disengages the moving element from the pallet.

In some cases, the moving elements engage and disengage with the palletsvia an engagement system comprising: a frame provided to the movingelement; a movable pin provided to the frame that is biased toward theengagement position; a movable cam mechanism provided at the workstationthat, when advanced, is configured to operate against the bias toretract the movable pin for disengagement with the pallet, and, whenretracted, allows the movable pin to engage with the pallet.

In some cases, the workstation further comprises: a workstation lockingmechanism that, when activated, locks the pallet in position at theworkstation, wherein the workstation locking mechanism is configured tooperate with the cam mechanism such that the pallet is engaged witheither of the workstation or the moving element at all times.

According to yet another aspect herein, there is provided a modularmulti-mode conveyor system comprising: at least one linear drive tracksection configured such that moving elements are independentlycontrolled and moved along the track section; and at least onemechanical drive track section having the same configuration as thelinear drive track section but wherein the linear drive is replaced witha scroll cam drive system and moving elements are controlled and movedalong the track section by the scroll cam drive system.

In a particular case, the modular conveyor may further comprise acontrol system for monitoring the movement of moving elements, whereinthe control system includes a moving element tracking system comprising:an encoder strip provided to the moving element; a plurality of encoderread heads provided to the track section and configured to read theencoder strip as moving elements move past the location of the encoderread heads.

In another particular case, the scroll cam drive system may include: acylindrical cam; a plurality of cam grooves formed on the cylindricalcam; a drive system for rotating the scroll cam; and each moving elementcomprises: a plurality of cam followers; wherein the plurality of camgrooves are configured to contact with respective ones of the pluralityof cam followers to move the moving elements. In this case, the camgrooves may be configured to provide a period in which a moving elementis not driven even though the scroll cam is rotating.

In another particular case, the linear drive track section may include amagnetic drive system.

According to still yet another aspect herein, there is provided a scrollcam conveyor system comprising: a scroll cam including: a cylindricalcam; a plurality of cam grooves formed on the cylindrical cam; a drivesystem for rotating the scroll cam; and a moving element comprising: aplurality of cam followers, wherein the plurality of cam grooves areconfigured to contact with respective ones of the plurality of camfollowers to move the moving element.

In a particular case, the cam grooves are configured to provide a periodin which a moving element is not driven even though the scroll cam isrotating.

In another particular case, the scroll cam conveyor system may furthercomprising a control system for monitoring the movement of movingelements, wherein the control system includes a moving element trackingsystem comprising: an encoder strip provided to the moving element; anda plurality of encoder read heads provided to the track section andconfigured to read the encoder strip as moving elements move past thelocation of the encoder read heads.

According to yet another aspect herein, there is provided a method ofdeveloping a cam profile for a cam driven system comprising a disk camand a cam follower for converting the disk cam motion into linear motionin order to drive a driven device, the method comprising: providing alinear actuator in contact with the cam follower at a location spatiallyrelated to the position of the disk cam; providing a processor tocontrol the movement of the linear actuator; determining an initialmovement profile for movement of the linear actuator; adjusting theinitial movement profile based on experimental runs of the driven deviceto develop a final movement profile; calculating a cam profile based onthe final movement profile; and outputting the cam profile for use informing a disk cam.

BRIEF DESCRIPTION OF DRAWINGS

The drawings included herewith are for illustrating various examples ofarticles, methods, and apparatuses of the present specification and arenot intended to limit the scope of what is taught in any way. In thedrawings:

FIG. 1 is a schematic diagram of a modular conveyor system;

FIG. 2 is a perspective view of a track section of the modular conveyorsystem of FIG. 1;

FIG. 3 is an expanded view of the track section of FIG. 2;

FIGS. 4A and 4B are perspective views of a moving element of the tracksection of FIG. 2;

FIG. 5 is a sectional view of the track section, moving element and partpallet;

FIGS. 6A and 6B are sectional views of the track section, moving elementand pallet showing engagement of the moving element with the pallet;

FIGS. 7A-7C are detailed perspective views showing engagement of themoving element with the pallet;

FIGS. 8A and 8B are block diagrams of an example distributed controlarchitecture for controlling the track section of FIG. 2;

FIGS. 9A to 9I illustrate the conveyor system in various positions andproviding multi-cycle, multi-pitch movement;

FIG. 10A illustrates another embodiment of a modular conveyor system inwhich a powered track section is used with an unpowered track sectionincluding a scroll cam drive system;

FIG. 10B shows the embodiment of FIG. 10A but without pick and placeelements;

FIG. 10C illustrates the use of the rotating scroll cam to guide themoving elements on a linear track via roller pins in a cam groove in thescroll cam;

FIG. 10D illustrates the engagement of the roller pin in the cam groove;

FIG. 10E shows the groove start opening for the cam grooves on thescroll cam;

FIGS. 11A-11C illustrate the scroll cam and the engagement with themoving elements;

FIGS. 12A and 12B illustrate a dual drive scroll cam and pick and placesystem;

FIG. 13A illustrates a cam drive system for a pick and place device;

FIG. 13B shows additional detail related to the cam drive system of FIG.13A;

FIGS. 130 and 13D illustrate the function and principle of engagementand disengagement of cam follower levers (coupling and de-coupling ofstations/zones);

FIG. 13E illustrates the substitution of cam discs by electricallydriven actuators;

FIGS. 14A-14D illustrate a single drive scroll cam and pick and placesystem.

DESCRIPTION

Numerous specific details are set forth in order to provide a thoroughunderstanding of the example embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein may be practiced without these specificdetails. In other instances, well-known methods, procedures andcomponents have not been described in detail so as not to obscure theembodiments described herein. Furthermore, this description is not to beconsidered as limiting the scope of the embodiments described herein inany way, but rather as merely describing the implementation of thevarious embodiments described herein. The embodiments described hereinare not intended to be limited to the specific details of any oneexample embodiment or to specific details that may be common tomultiple, or all, example embodiments. The applicants, inventors orowners reserve all rights that they may have in any embodimentsdisclosed herein, for example the right to embodiments claimed in acontinuing application, and do not intend to abandon, disclaim ordedicate to the public any such embodiments by disclosure of thisdocument.

FIG. 1 shows a general schematic diagram of a modular conveyor system20, which will be used to provide a general description of the system.

The system 20 includes an infeed conveyor 25, which delivers pallets 30to a track section 35. The infeed conveyor 25 may be, for example, abelt conveyor, conveyor known in the art, or the like. As the pallets 30arrive at an infeed station 40, they are detected and held at the infeedstation 40 by a holding mechanism 45, such as a gate, lock or the like.In fact, several pallets 30 may be held at the infeed station 40depending on the operating status of the system 20. A moving element 50mounted on the track section 35 engages with the pallet 30 at the infeedstation 40 and, after release from the holding mechanism 45, the movingelement 50 moves the pallet 30 onto a pallet rail 55 that is positionedadjacent the track section 35 and transports the pallet 30 in anindependently controlled manner to a workstation 60. As will beunderstood, the pallet 30 may include some means (not shown) to reducefriction on the pallet rail 55 to allow the moving element 50 to movethe pallet 30. At the workstation 60, the pallet 30 is accuratelypositioned by the moving element 50 and then held in a place by alocking mechanism (not shown in FIG. 1) provided at the workstation 60.The workstation 60 typically includes an apparatus (not shown) such thatan operation, for example a pick and place or other operation, can beperformed on a workpiece (not shown), such as a part, device or the likethat is being carried by the pallet 30. While the pallet 30 remains atthe workstation 60, the moving element 50 can be disengaged from thepallet 30 and is free to move and collect a subsequent pallet 30 whileanother moving element 50 may return to connect with the pallet 30 atthe workstation 60. In this way, the movement of each pallet 30 fromworkstation 60 to another workstation 60 is carried out by moving aplurality of moving elements 50 along the track section 35, each movingelement 50 being independently controlled.

In situations where multiple operations are performed while a particularpallet 30 is at a workstation 60 (multi op), the moving element 50 mayremain engaged with the pallet 30 while the pallet 30 is at theworkstation 60 and can provide any x-axis movement required for theoperations. In this situation, it will be understood that the movingelement 50 which moves the pallet 30 to the first workstation 60 couldremain engaged with the pallet 30, in which case the moving element 50would return to collect a new pallet 30 after the operations arecompleted. Alternatively, a second moving element 50 could engage withthe pallet 30 for the various operations. The particular arrangementwill depend on the timing of operations at different workstations 60along the track section 35.

Generally speaking, each pallet 30 may then be moved/indexedindependently and accurately through any number of workstations 60 (fourshown) and via any number of track sections 35 (two shown).

At the end of all workstations 60, each pallet 30 is moved to an outfeedstation 65 where it is moved onto an outfeed conveyor 70 by a movingelement 50 and is disengaged. This releases the pallet 30 to be carriedby the outfeed conveyor 70 to the next processing operations (notshown). In some embodiments, a sensor (not shown) may be provided at theoutfeed station 65 or on the outfeed conveyor 70 to monitor a buffer tothe next processing cell in order to slow or stop the conveyor system 20if the buffer is full or becoming full. As with the infeed conveyor, theoutfeed conveyor may also be a conventional conveyor such as a beltconveyor or the like.

This combination of conventional infeed and outfeed conveyors with theindependently controlled track sections provides for a lower costmodular conveyor system because it makes use of cheaper, conventionalpallets 30 and a limited number of independently-controlled movingelements 50 for each of the track sections 35. The use of cheaperconventional conveyor types also allows flexibility in design ofmanufacturing lines by allowing operations that do require detailedcontrol to be performed on the track section and operations that do notrequire as much detailed control to be performed on the conventionalconveyor.

The modularity and independent control provided by the track sections 35also make it easier to retool the modular conveyor system 20 as eachworkstation 60 can be provided at any point along the track section 35and can be adjusted quite easily based on the independent control.Further, the modularity allows for a plurality of track sections 35 tobe included together to provide as large a processing area as needed fora particular process and the flexibility to adjust the layout as needed.

FIG. 2 illustrates a track section 35 of the modular conveyor system 20.The track section 35 features one or more moving elements 50 (only oneis illustrated) which are configured to ride or travel along a track 75.The track 75 includes a frame 80 configured to support the movingelement 50 on an upper runner 85 and lower runner 90. Some of theprinciples of operation of the track section 35 are described in moredetail in U.S. Pat. RE39,747 to Peltier, which is hereby incorporatedherein by reference.

The modular conveyor system 20 can be composed of a plurality of tracksections 35 which are mechanically self-contained and quickly and easilyseparable from one another so as to be modular in nature. In thisembodiment, the track sections 35 are mounted on a support (not shown)so as to align and abut one another in order to form a longer track. Inorder to be modular, each track section 35 preferably houses all of theelectronic circuitry required to power and control the track section 35.

FIG. 3 illustrates an expanded view of the track section 35. The frame80 houses a linear drive mechanism 95 that is formed as a statorarmature 100 comprising a plurality of embedded coils 105 which areindividually excited so that an electrically-induced magnetic fluxproduced by the stator armature 100 is located adjacent to a givenmoving element 50 to be controlled, in a direction normal thereto,without affecting adjacent moving elements 50. The coils 105 arearranged as a sequence of individual polyphase-like windings or coilsets, wherein coils in each set are overlapped such that the coilcentres are spaced apart. The frame 80 also includes a bus bar 110 toprovide power to the stator armature 100. The motive force fortranslating each moving element 50 arises from the magnetomotive (MMF)force produced by each moving element 50 and the stator armature 100,i.e., by the tendency of the corresponding magnetic fluxes provided bythe stator armature 100 and moving element 50 to align. A servocontrolsystem (described below) enables separate and independent moving MMFs tobe produced along the length of the track section 35 for each movingelement 50 so that each moving element 50 can be individually controlledwith a trajectory profile that is generally independent of any othermoving element 50. Structurally, the track section 35 may thus bebroadly classified as a moving-magnet type linear brushless motor havingmultiple moving elements 50.

FIGS. 4A and 4B illustrate perspective views of the moving element 50and FIG. 5 shows a sectional view of the track section 35, movingelement 50 and pallet 30. As shown in FIG. 4A, each moving element 50includes a body 115 which houses one or more permanent magnets 120disposed to provide a magnetic flux orientated normal to the tracksection 35. In the example configuration of FIG. 4A, the magneticstructure of each moving element 50 comprises two thrust-producingpermanent magnets 120 arranged in alternating North-South sequence. Thepermanent magnet material, which may include Neodymium-Iron-Boron,Alnico and ceramic (ferrite) base magnets, is generally selected on thebasis of air gap flux densities required and the physical dimensions ofthe moving element 50 magnetic structure.

As shown in FIGS. 4A, 4B and 5, each moving element 50 features upperwheels 125 and lower wheels 130 which ride along upper and lower runners85, 90 of track 75. In this particular embodiment, the upper wheels 125are angled to match with the angled upper runner 80 to provide adownward force on the moving element 50 and help prevent the movingelement 50 from separating from the track 75. It will be understood thatalternate arrangements may provide the same functionality. The movingelement 50 is also provided with anti-tip blocks 135 that can interactwith the frame 80 to help prevent the moving elements 50 from tipping ifthere is a collision or the like. The moving element 50 may also includestatic brushes 145 that assist with dissipating any build up of staticelectricity.

As further seen in FIGS. 4A and 5, each moving element 50 includes anextension 150 onto which is mounted an encoder strip 155, which may be,for example, an optically transmissive or reflective strip, a magneticstrip, other type of feedback system or the like. The extension 150 isconfigured such that the encoder strip 155 interacts with encoder readheads 160 mounted to a corresponding extension 165 extending from thetrack 75 (see FIG. 5). The encoder read heads 160 are configured to readthe encoder strip 155, whether optically, magnetically or otherwise. Theencoder strip 155 and encoder read heads 160 form an encoder system 157.The inter-engaging structure is intended to protect the encoder system157 from the traffic on the track 75 and dust and other debris. Theencoder system 157 is employed in the moving element position-detectingsubsystem explained in greater detail below. At this point, it should beappreciated that by placing the encoder read heads 160 on track 75 andnot on moving elements 50, the moving elements 50 are not tethered inany way and thus their mobility is not restricted.

As seen in FIG. 4B, the moving element 50 also includes an engagementmechanism 170 that allows the moving element 50 to engage with thepallets 30 (also referred to as the moving element portion of the palletengagement mechanism). In this particular embodiment, the engagementmechanism 170 includes a mounting plate 175 (also referred to as aframe) provided with pins 180. The mounting plate 175 is spring-biasedsuch that pins 180 are in an extended position above the moving element50. The engagement mechanism 170 is described in further detail belowwith regard to FIGS. 6A and 6B. It will be understood by those of skillin the art that alternate engagement mechanisms may also becontemplated, including non-contact engagement mechanisms such asmagnetic engagement mechanisms.

FIGS. 6A and 6B illustrate the disengagement of the moving element 50and the pallet 30 at the workstation 60. As shown in FIG. 6A, the movingelement 50 arrives at a workstation 60 engaged with a pallet 30. As afirst stage, a workstation locking mechanism 185 engages with the pallet30 to hold the pallet 30 in place adjacent the workstation 60. In FIG.6B, as a second stage, a pallet engagement mechanism 190 provided at theworkstation 60 (in this case, a movable cam, sometimes referred to asthe workstation portion of the pallet engagement mechanism) is advancedforward to lower the mounting plate 175 and pins 180 from the movingelement 50 such that the moving element 50 is disengaged from the pallet30. The moving element 50 is then free to move along the track section35 while the pallet 30 remains locked at the workstation 60.

FIGS. 7A to 7C illustrate engagement of the moving element 50 with thepallet 30. FIG. 7A shows the moving element 50 approaching theworkstation 60 where the pallet 30 is locked by the workstation lockingmechanism 185. The pallet engagement mechanism 190 also remains advancedtowards the pallet 30 in the position from FIG. 6B described above. FIG.7B shows the moving element 50 engaging with the pallet engagementmechanism 190 at the workstation 60 such that the mounting plate 175 andpins 180 on the moving element 50 are lowered prior to engagement withthe part pallet 30. In FIG. 7C, as a first stage, the pallet engagementmechanism 190 has been retracted to allow the mounting plate 175 andpins 180 to rise and engage with the part pallet 30. Following theengagement, as a second stage, the workstation locking mechanism 185 isretracted to allow the pallet 30 to move with the moving element 50.

The use of a two stage mechanism ensures that the part pallet is engagedwith the moving element 50 before release from the workstation 60 orlocked at the workstation 60 before disengagement from the movingelement 50. This approach is intended to ensure that the pallet 30 isalways accurately positioned either at a workstation 60 or in relationto a moving element 50.

FIG. 8A is a block diagram of an example control architecture employedin the conveyor system 20. As shown in FIG. 8A, the conveyor system 20includes a central controller 200 that controls the overall conveyorsystem 20 and a section controller 205 for each of the track sections 35used in the conveyor system 20 (four section controllers 205 are shown).As described above, the conveyor system 20 can be formed from aplurality of modular track sections 35, representing control zones,which are controlled by a section controller 205. The central controller200 may monitor destination data for the moving elements 50 (which arepreferably uniquely addressed) and receive acknowledgement messages inreturn when moving elements 50 have reached their destinations. As such,the central controller 200 may be used for process (i.e.manufacturing-line) control. The central controller 200 may also providea supervisory diagnostic role by monitoring the section controllers 205(e.g., by engaging in a continuous polling process) in order todetermine whether any section controller 205 has failed. It will also beunderstood that the central controller 200 may also provide control forthe infeed conveyor 25 and outfeed conveyor 70, for example via infeedcontroller 207 and outfeed controller 209.

FIG. 8B is a block diagram of an example control system 210 for a tracksection 35. The control system 210 includes the section controller 205that is connected to the central controller 200 via an input/output(I/O) or network module 215. In this embodiment, the section controllers205 are connected to one another in a peer-to-peer communicationsnetwork such that each section controller 205 is connected to precedingand following section controllers 205 through a communications links220. It will be understood that other alternative embodiments mayinclude use of the central controller 200 to convey information/databetween section controllers 205 or the like.

The section controller 205 may also be connected to other devices, suchas programmable logic controllers (PLCs) (not shown) via input/output(I/O) or network modules 215. The PLCs may provide manufacturing-linestation-processing instructions to the track section 35, such asdirecting the next destination for a moving element 50 along the track75, or providing station-specific motion instructions in respect of agiven moving element 50 stopped adjacent to a workstation 60. Forinstance, a typical two-axis station controller or PLC may operate byproviding pulse signals in order to synchronize the motion of a movingelement 50 along the track 75 with the motion of a station end effector(not shown) or the like moving along a transverse axis, whereby eachpulse represents an incremental move command for the moving element 50.It will be appreciated that the provision of the direct connection tothe PLC reduces the amount of bandwidth that would otherwise be requiredto communicate this information through the central controller 200,thereby substantially eliminating a potential limitation on the lengthand processing capabilities of the track section 35.

As illustrated, each section controller 205 is connected to the statorarmature 100 and coils 105 in the corresponding track section 35 andcontrols the coils 105 in accordance with an independent trajectory or“move” command for each moving element 50 located therein.

Each track section 35 also includes power balancing electronics 225 thatmay include, for example, current amplifiers, current sensing circuitry,temperature sensor, voltage sensors and the like. The section controller205 may periodically poll the power balancing electronics 225 in orderto obtain diagnostics data provided by these sensors.

Each section controller 205 is also connected to the encoder read heads160 situated in the track section 35. The section controller 205 is usedto implement a closed-loop digital servo control system that controlsmovement of the moving element 50 by resolving the absolute position ofeach moving element 50 located in its track section 35. The sectioncontroller 205 makes use of a moving element position feedbacksubsystem, which supplies measured moving element position data to thesection controller 205. Referring to FIGS. 4A, 4B and 5, when theencoder strip 155 of a given moving element 50 moves over a givenencoder read head 160, signals are produced and cause the sectioncontroller 205 to update the position of the moving element 50 inaccordance with the direction of travel of the encoder strip 155. Thesection controller 205 provides processing for sampling the encoders 160and resolving the position of each moving element 50 located in theassociated track section 35. Broadly speaking, the processing associatesthe encoder strip 155 of any given moving element 50 with only oneencoder 160 at any time so that the absolute position of the givenmoving element 50 can be calculated based on a fixed position of theassociated encoder (or more specifically its read head 160) and arelative position of the encoder strip 155 in relation to the associatedencoder 160. In addition, when the encoder strip 155 simultaneouslyengages two encoders 160, the processing transfers or hands-off theassociation or “ownership” of the moving element 50 from the currentencoder 160 to an adjacent engaged encoder 160. In this manner, theposition of a given moving element 50 can be continuously tracked acrossthe control zone. When a moving element 50 crosses control zones, asimilar process occurs, with the addition that the adjacent sectioncontroller 205 creates a data structure to keep track of the position ofthe given moving element 50, and, once the hand-off is completed, thedata structure for the moving element 50 in the (now) previous controlzone is deleted.

As one example, if a 400 lines-per-inch graded encoder strip 155 movesone inch through a given encoder read head 160, such movement will causean associated counter to change by +/−400, depending on the direction oftravel. This type of encoder read head 160 as well as the associatedencoder strip 155 are commercially available, for instance, from USDigital of Washington, U.S.A. The encoder strip 155 may further includean incremental encoder portion (not shown) having a plurality of indexpoints staggered along the strip such that the moving element 50 can belocated based on reading as few as two index points.

Those skilled in the art will appreciate that the encoder system 157 maybe optical or may be another alternative system. For example, a passivereadable device can be a magnetic strip and the encoder read heads canbe corresponding magnetic detectors. Such an alternative embodiment mayprovide very fine resolution.

FIGS. 9A-9I illustrate operation of the conveyor system 20 in a multicycle time, multi pitch arrangement. As shown in FIG. 9A, pallet F is ata first workstation S1 and pallet E is at the infeed singulator awaitingprocessing. At this stage, moving element 1 engages with pallet E andmoving element 2 engages with pallet F. In FIG. 9B, moving element 2 hasadvanced pallet F to an intermediate position between the firstworkstation and a second workstation S2. At the same time, movingelement 1 moves pallet E to the first workstation S1.

In FIG. 9C, moving elements 1 and 2 move back up the track such thatmoving element 1 is aligned with and engages pallet D at the infeedsimulator and moving element 2 is aligned with and engages pallet E atthe first workstation S1. At the same time moving elements 3, 4, 5, 6and 7 align with and engage pallets F, G, H, I, J. In FIG. 9D, movingelements 1 through 7 have advanced together with associated pallets andrelease pallet D at the first workstation S1, pallets E and F at thesecond workstation S2, pallets G and H at the third workstation S3 andpallets I and J at an intermediate position between the thirdworkstation S3 and the fourth workstation S4. As is apparent in FIG. 9D,the pallets can be positioned independently at workstations 60 havingvariable pitches and operating on multiple pallets at the same time.

In FIG. 9E, moving elements 1 and 2 return to the beginning of the tracksuch that moving element 1 is in a position adjacent to and engages withpallet C at the infeed singulator and moving element 2 is positionedadjacent to and engages with pallet D at the first workstation S1. Asshown in FIG. 9F, moving elements 1 and 2 then advance pallets C and Dsuch that pallet C is positioned at the first workstation S1 and palletD is positioned at an intermediate position between the firstworkstation S1 and the second workstation S2. This movement preparespallet D for advancement into workstation S2 which operates as a “2 up”workstation.

As shown in FIG. 9G, moving elements 1 to 13 are positioned adjacent toand engage with pallets B to N. In FIG. 9H, moving elements 1 to 13advance, moving pallets B through N forward along the track. Pallet B ispositioned at the first workstation S1, pallets C and D are moved intothe second workstation S2, pallets E and F are moved into the thirdworkstation S3, pallets G, H, I, J are moved into the fourth workstationS4, and lastly, pallets K, L, M, N are moved onto the outfeed conveyorwhere they can be sent for additional processing.

In FIG. 9I, the moving elements 1 and 2 return to the beginning of thetrack where moving element 1 is adjacent to and engages with pallet Aand moving element 2 is adjacent to and engages with pallet B atworkstation S1. At this point, the process continues repetitively.

It will be understood that FIGS. 9A-9I illustrate just one possiblearrangement of workstations, pallets, and moving elements to illustratethe ability of the conveyor system 20 to advance pallets through aprocess that has multiple pitches, multiple cycle times and workstationsthat operate on more than one pallet at a given time, based on the cycletimes involved.

When dealing with magnetic linear drive systems such as that describedabove, one issue can be the addition or removal of the moving elements50. In order to overcome this concern, a modular track section may beprovided with an extension, for example, approximately 300-600 mm (12-24inches) long, that is not provided with an encoder or motor section. Forremoval or addition, the moving element 50 can be manually moved to thisextension section and removed or placed on this extension section andpushed back onto a powered track section.

In the modular conveyor system, part tracking data can be tracked byproviding a sensor or reader (not shown) to obtain part information atthe infeed station. The part data can then be associated with individualmoving elements 50 or workstations 60 as the pallet 30 moves through thetrack section. As such, part data and position can be tracked accuratelythroughout the track sections 35.

In the situation where there is a failure of the system of some kind andit is necessary to reset the system in order to identify individualmoving elements 50 and locations, a process can be used to reorient themoving elements 50 of the system. In a particular embodiment, all movingelements 50 can be manually moved to a downstream position. On startupthe system can move all moving elements 50 upstream to a pre-programmedtarget position at which point moving element IDs can be assignedsequentially from a programming logic controller. After the ID isassigned, the moving elements 50 can be released by the PLC to go to adedicated pick position target. In some cases downstream moving elements50 may be released to upstream holding targets until the most downstreammoving element 50 has been sent to its pick position target. It will beunderstood that the number of holding targets will depend on thephysical layout. This type of recovery sequence can be coordinated bythe PLC and has the benefit that no RFD or IR or other moving element IDsystem is generally required.

Each track section 35 or each combination of track sections 35 can beprovided with both mechanical and software limits in order to preventmoving elements 50 from running off at the end of the track section 35or combination of track sections 35.

As the modular conveyor system 20 includes both powered track sectionsand mechanical infeed and outfeed conveyors, operator stations can beprovided outside of a guarded area that may be provided for the higherpower track sections 35 which provide the independent control. Thisprovides for greater safety for operators. The use of mechanical infeedand outfeed conveyors allows for more buffering flexibility in betweenareas on the manufacturing line. For example, a conventional conveyormay be placed in between two linear-drive areas to allow for cheaperbuffering if one linear-drive area is stopped for any reason. Theappropriate use of buffering can improve overall equipment effectiveness(OEE).

This combination modular conveyor system 20 has advantages overconventional systems in that the pallet size is not limited by thechassis pitch and multiple parts can be provided on one pallet. On thetrack sections 35, each moving element 50 can be moved independently toallow for offsetting at one workstation 60 while performing a multioperation at another workstation 60, and full access to the part fromall sides is provided within the track sections 35. Further, because ofthe accurate indexing on the track sections 35, the moving element 50may provide x-axis movement to provide for coordinated motion with y andz axes devices at the workstation 60.

Embodiments of the modular conveyor system 20 disclosed herein aregenerally intended to provide a number of advantages over conventionalconveyor systems. For example, the use of relatively inexpensiveconventional conveyors for part transport reduces costs while theindependently controlled moving elements 50 of the track section 35 canbe used for precise control of position. Further, the electromagneticstructure of the track sections 35 provides smooth thrust and high speedwhile maintaining accurate positioning. Furthermore, the distributedcontrol system enables each moving element 50 to be individually andseparately controlled yet interface easily with manufacturing processcontrollers for infeed and outfeed conveyors. Finally, the conveyorsystem 20 can be constructed out of discrete, self-contained, modulartrack sections 35 and infeed and outfeed conveyors, with littlepractical restriction on the length of the conveyor system or the numberof moving elements 50 controlled thereby.

FIG. 10A shows a further embodiment of the use of modular track sections35 together with a mechanical conveyor 400. In this case, rather than aconventional belt conveyor, the mechanical conveyor 400 comprises ascroll cam 405 provided to a modular track section 35′ that has had thelinear drive removed (or alternatively, turned off), referred to as anunpowered track section 35′. As shown in FIG. 10A, pick and placeelements 410 may be provided with the powered track section 35 orunpowered track section 35′. FIG. 10B shows a view of this embodimentwith pick and place elements removed. In this embodiment, the movingelements 50 are configured to move off of the powered track section 35and along the unpowered track section 35′. As with the embodimentsabove, the moving elements 50 may be provided with a pallet 30 that isengaged with the moving element 50 such that the pallet 30 moves withthe moving element 50 as the moving element 50 moves along both poweredand unpowered track sections 35 and 35′.

As a moving element 50 passes from a powered track section 35 to anunpowered track section 35′, the driving of the moving element 50 ispassed from the linear drive 75 to the scroll cam 405. FIGS. 10C and 10Dshow the scroll cam 405 and moving element 50 in additional detail. Thescroll cam 405 includes a cam groove 415 (or multiple grooves—twogrooves 415 in this embodiment) that engages with one or more camfollowers 420 (in this case, a roller pin) on the moving element 50 andadvances the moving element 50 along the unpowered track section 35′.FIGS. 10C and 10D illustrate how a pitch of the groove 415 interactswith the cam follower 420 to transfer circular motion into linearmotion. The scroll cam 405 can be rotated forward or backwards and thesense of rotation determines the direction of motion of the movingelement 50 through the engaged roller pin 420 in the cam groove 415. Thecam groove 415 can be configured for various types of movement of themoving element 50 along the unpowered track section 35′, including shortstationary periods, pitched movement, continuous movement, or the like.FIG. 10E illustrates a configuration of a groove 415 that includes agroove start arrangement 425 to allow the groove 415 to collect the camfollower 420.

It will be understood that the scroll cam enabled unpowered tracksections 35′ will also be configured as modular sections that can bejoined, either with powered track sections 35 (linear drives) or withother unpowered track sections 35′ wherein two scroll drives 405 may beconnected to each other to provide a longer scroll drive 405 andunpowered track section 35′ of an assembly line.

Elements from the powered track section 35 embodiments described above,such as the encoder system 157, may remain in place where effective. Inthe case of the encoder system 157, the encoder system 157 may remain onthe unpowered track section 35′ and the moving element 50 in order toallow accurate tracking of the moving element 50 as it moves along theunpowered track section 35′. The use of a standard modular track sectionthat may have a linear drive or a mechanical drive, such as the scrollcam 405 is intended to allow for the creation of flexible automationsystems.

It will be understood that alternative embodiments may allow the pallet30 to be separated from the moving element 50 (as in the in feedconveyor 25 and out feed conveyor 70 of the initial embodiments above)and the pallet 30 may be advanced in the unpowered track section bybeing engaged with the moving element 50 (in interaction with the scrollcam 405) or by the scroll cam 405 directly, for example, by providingcam followers (not shown) to the pallet 30 and disengaging the pallet 30from the moving element, similar to the engagement and disengagement ofthe moving element 50.

An intended advantage of the present embodiment is being able to runnon-synchronous (powered track section) to synchronous (unpowered tracksection) without a change over to a different track system. It ispossible to run smoothly from non-synchronous to synchronous (sometimescalled “continuous motion”) and back to non-synchronous oralternatively, to start with synchronous and then to non-synchronous,all in a single modular track environment. It will be understood thatthe modularity of the track sections 35 and 35′ make it possible to haveany required number of drive system changeovers succeeding one anotherin order to create an assembly line or the like.

In some embodiments, pick and place motion can be handled by a separatepick and place drive system 430 (as shown in FIG. 10A), in which case aPLC (programmable logic controller) (not shown) can be used tocoordinate pick and place and moving element motion control. In otherembodiments, pick and place motion may be directly coupled with movingelement motion (further description below), in which case, both thescroll cam 405 (providing pallet motion) and the pick and place 410 maybe driven by a common drive. In this case, it will generally be moreimportant to have the scroll cam 405 undergoing continuous movement. Inthis situation, it is still possible to temporarily halt the movement ofa moving element 50 (or pallet 30) by providing cam grooves 415 thatfollow the rotational movement of the scroll cam 405 around itscircumference. This configuration can create a brief “dead zone” wherethe moving element 50/pallet 30 will not move even though the scroll cam405 is turning. It will be understood that any temporary halts or deadzones will be limited by the circumference of the scroll cam and therate of rotation.

In the embodiment illustrated in FIGS. 10A to 10E, the ability to drivepallet movement by linear drive followed by scroll cam is intended toinclude benefits such as:

-   -   a. the use of lower cost scroll cam based motion control where        suitable with flexibility of using linear drive control where        required for processing requirements;    -   b. the ability to de-couple large cam based systems into        multiple zones (modularity) providing improved integration        flexibility, maintenance/serviceability, and providing flexible        buffering between cam zones using linear servo control; and    -   c. the ability to perform liquid filling and other wet        operations in the cam based zone thereby protecting the linear        drive sections from potential liquid damage.

In some cases, the scroll cam 405 may preferably use two camgrooves/guides 415 matched to two roller pins (cam followers 420)provided on the moving elements 50 to provide the guided motion (asshown in FIGS. 10A-10E). FIGS. 10C-10E shows a sample scroll cam with 2parallel grooves (sometimes called “twin grooves”). The circular(angular) positions of the groove-starts 425 on the scroll cam 405 areconfigured to engage the roller pins 420 of an arriving moving element50 as can be seen in FIG. 10E. FIGS. 11A to 11C illustrate movingelements 50 on the unpowered track section 35′. As the moving element 50arrives at the unpowered section 35′, the scroll cam 405 commencesrotating and the groove-start 425 (see FIG. 10E) engages a first rollerpin 420A (see FIG. 11C) positioned near the front of the moving element50, bringing the first roller pin 420A into a first groove 415A. Thedistance between the two grooves 415A and B on the scroll cam 405 leadsto respective angular offset of the groove-start 425 related to thefirst groove 415A and second groove 4158. A second roller pin 4208 isthen engaged by the second groove 415B. Varied shapes of the grooves 415on the scroll cam 405 can allow for changing speed and accelerationduring motion, which, as noted above, can be particularly important withcontinuous drive systems and, in particular, a system where both thescroll cam 405 and the pick and place 410 are driven by a single drive(discussed below). The use of two or more grooves 415 with two or morecam followers 420 also provides for additional stability in positioningthe moving elements 50 because the cam grooves 415 and the cam followers420 can be positioned such that each cam groove 415 applies pressure ona different side of the respective cam follower 420 such that there willbe less play of the cam followers 420 within the grooves 415.

The intended benefits include:

-   -   a. good tolerance position repeatability due to the use of two        grooves 415;    -   b. reduction in wear providing a longer life of cam and roller        pins; and    -   c. scroll cam can be more easily designed to suit required pitch        and motion profile required (e.g. pallet acceleration and        velocity, continuous motion vs. pallet dwell time in station).

An additional benefit of the use of two or more cam grooves 415 and camfollowers 420 is the ability of the scroll cam 405 to pull the movingelement 50 off of the powered track section 35 by engagement with thefirst (i.e. forward) cam follower 420A and then, in turn, “push” themoving element 50 onto a subsequent powered track section 35 or the likeby continuing to apply forward force to the moving element 50 via thesecond cam follower 420B even after the frist cam follower 420A hasdisengaged. Although not shown, it will be understood that the first andsecond cam followers 420A and B may in fact be positioned on anextension slightly ahead of or behind the moving element, depending onthe particular use of the system.

As described above, a plurality of drives may be used for driving thescroll cam 405 and pick and place units 410 (one or more for the scrollcam 405, one or more for the pick and place units 410). The multipledrive solution offers more flexibility for the operation of the pick andplace handling, for instance if a longer stoppage of a pallet on the camdriven section is necessary. One example of a dual drive is shown infurther detail in FIGS. 12A and 12B. In this case, the scroll cam drive435 can be stopped while the pick and place drive 440 continues tooperate. As noted above, a single (common) drive solution can enable astoppage of the pallet but generally only for a time period less thanone single rotation of the scroll cam (realized through the course/shapeof the cam grooves 415. Multi drive systems need to be synchronized viathe PLC. In some cases, using servo motors as drive sources for the pickand place units 410 can enable the PLC at any moment to “know” thecurrent position of the moving element 50 and the pick and place unit410. When using multiple drives, intended benefits include:

-   -   a. Flexibility to de-couple zones without additional cost of        decoupling drives and the like. The decoupling can be realized        by simple “switching off” the respective zone/station. Not        necessary to de-couple by mechanical means.

One example of a pick and place drive 440 involves a cam driven pick andplace as shown in more detail in FIG. 13A-13D. In this case, rotatingcams 500A and 5008 drive horizontal and vertical motion, respectively.The rotating cams 500A and 500B drive cam followers 505 (only 505A isshown), which are supported by cam levers 510A and 510B. The cam levers510A and 510B are connected transmission systems 515A and 515B totransmit the motion into the appropriate horizontal and vertical pickand place motion. The cam levers 510A and 510B are also connected withcylinders 520A and 5208, for example, a pneumatic cylinder or the like.The pneumatic cylinder 520A and 520B act as a spring to maintain the camfollower 505A (via the cam lever 510A and 510B) in contact with therotating cams 500A and 500B. FIG. 13B illustrates the functionalprinciple of the pick and place unit. Coupling and de-coupling of thepick and place unit 410 is performed pneumatically by extending orretracting the cylinder 520A or 520B with pressurized air. When engaged,the cylinder 520A or 520B pulls the lever down to the rotating cam 500Aor 500B but also functions as an air spring due to the compressibilityof the air in the cylinder 520A or 520B. FIGS. 13C and 13D illustratethe use of the cylinder 520A and 520B as an air spring (downward arrow522) or to disengage the pick and place (upward arrows 523). Intendedbenefits of this system include:

-   -   a. reduced wear through roller follower 505A to hardened        rotating cam 500A (FIG. 13 b); and    -   b. ability to de-activate pick and place motion via programmable        control (the pneumatic cylinder can be extended to disengage the        cam and thereby stop pick and place motion). FIGS. 13C and 13D        illustrate how engagement/disengagement of the cam lever/cam        follower is realized. A PLC may control the pneumatic cylinder        depending on the pick and place requirements for the processed        product.

Another example of a pick and place drive is a linear actuated pick andplace (FIG. 13E). As shown in FIG. 13E, linear actuators (servo orotherwise) 525A and 525B are placed at the location of the pneumaticcylinder and the rotation cams 500A and 500B are removed. In this case,the pick and place is driven by the linear actuators 525A and 525B suchthat adjustment of the x and y dimensions of the pick and place movement(see arrows 527) can be performed easily via computer control of thelinear actuators 525A and 525B. Intended benefits include:

-   -   a. Programmable vertical and horizontal motion providing the        ability to rapidly develop pick and place motion profiles        without machined cam profiles;    -   b. Programmable flexibility to change pick and place vertical        and horizontal motion for different product or processing        requirements without having to change out cams.

In this example, the linear actuators 525A and 525B may alternatively beused only initially to allow for fast, efficient adjustment of the pickand place movement while developing a movement profile. Followingadjustments made using the linear actuators 525A and 525B a hardware camcan be formed based on the finalized movement profile and the hardwarecam can then be put in place to drive the pick and place with pneumaticcylinders 520A and 520B replacing the linear actuators 525A and 525Bonce the optimal cam profile has been developed. The initial use of thelinear actuators 525A and 525B helps to avoid the need to rework orwaste cam material (due, for example, to re-cutting the cam for eachadjustment) while developing the most appropriate cam profile for therequired motion.

In some cases, it may be less desirable to replace the linear actuators525A and 525B with a conventional cam system. For example, theprogrammability of the linear actuators 525A and 525B may provideadditional benefits for adjusting the movement profile in relation toother variables that may change in the manufacturing environment overtime. If a change is made in the processing of a product, theprogrammability of the linear actuators 525A and 525B can be used toadjust the pick and place motion to compensate. In a medicalproduct/device marketplace where strict validation requirements are inplace for manufacturing, if the programmable aspect of the linearactuators 525A and 525B has been validated in advance, the whole processmay not need to be re-validated because of the small change. Anotheradvantage is the increased flexibility regarding type changes and typevariety which will be possible by adjusting programming or evenselection of the respective production recipe including an appropriatemotion profile. Using linear actuators 525A and 525B in the pick andplace unit 410 on an ongoing basis may also enable vision controlledpick and place control, for example, it may be possible to include avision system that provides feedback to the linear actuators 525A and525B to adjust the movement of the pick and place based on a visuallydetermined location of a part. Such a system may be used to increaseaccuracy of gripping processes when a part's geometry or position on apallet differs from pallet to pallet.

Also as described above, a single drive may be used for both the scrollcam 405 and pick and place units 410. FIGS. 14A, 14B, 14C and 14D showan example of a single drive system 600 in which both the scroll cam 405and a pick and place system 605 are driven by a single drive 610. Inthis case, the pick and place system 605 includes a plurality of topmounted pick and place units 410. As shown in FIGS. 14B-14D, the singledrive 610 of this embodiment uses dual shaft motion control. Inparticular, the single drive 610 uses a gear box (not shown in detail)that is configured such that a drive motor 615 drives both the pick andplace system 605 via two drive shafts 620 and the scroll cam 405 via abelt 625. In this case, the drive shafts 620 can be geared with thesingle drive 610 such that they do not fully rotate but articulatethrough an arc range of motion (back and forth) and provide motion tolinkages 630 to drive each pick and place unit's 410 horizontal andvertical motion. Intended benefits of this arrangement include:

-   -   a. reduced drive cost with single drive 610 driving all pick and        place units 410 and scroll cams 405 in multiple zones;    -   b. reduced programming as moving element 50 motion and cam pick        and place units 410 are mechanically coupled;    -   c. ease and flexibility of positioning pick and place units 410        anywhere along the drive shafts 620 resulting in fast set-up and        quick re-configuration;    -   d. modular to re-position entire set of pick and place units 410        anywhere along unpowered track section 35′;    -   e. reduced footprint consuming less space as compared to        alternative pick and place configurations; and    -   f. lower cost pick and place.

While the single drive system 605 has been described in relation to usewith an unpowered track section 35′, it will be understood that thisfunctionality may be used with many types of conveyor systems that makeuse of a scroll cam 405 and pick and place units 410. Further, it willbe understood that, while the term pick and place has been used in theabove embodiments, other types of appropriate workstations may also beimplemented in place of the pick and place units 410.

The embodiments herein have been disclosed with a certain degree ofparticularity for the purpose of description but not of limitation.Those skilled in the art will appreciate that numerous modifications andvariations can be made to the embodiments without departing from thespirit and scope of the application.

While the above description provides examples of one or more processesor apparatuses, it will be appreciated that other processes orapparatuses may be within the scope of the disclosure. It will also beunderstood that the processes and apparatuses may be implemented usinghardware or software components or an appropriate combination thereof.Software may be provided as instructions on a physical computer mediumor the like for execution on a processor of a computing device.

I/We claim:
 1. A conveyor system comprising: a track section comprisinga control system, a drive system that is controlled by the controlsystem, a plurality of moving elements that are driven by the drivesystem, and a pallet support apparatus; and a plurality of pallets thatare configured to engage with the moving elements and move on the palletsupport apparatus; and a plurality of workstations provided along thetrack section, each workstation at a predetermined pitch from each otherworkstation, wherein at least some of the pitches are different amongworkstations, wherein the control system, drive system and movingelements are configured such that each pallet of the plurality ofpallets is independently advanced through the workstations based on thepitches of the workstations.
 2. A conveyor system according to claim 1,wherein each workstation has a predetermined cycle time and at leastsome of the cycle times are different among workstations and wherein thecontrol system, drive system and moving elements are configured suchthat each pallet of the plurality of pallets is independently advancedthrough the workstations based on the cycle times of the workstations.3. A conveyor system according to claim 1, wherein the drive systemcomprises a magnetic drive system and each moving element comprises amagnetic conductor.
 4. A conveyor system according to claim 2, whereineach workstation is provided with a workstation locking mechanism thatis configured to lock a pallet in position at the workstation for thecycle time.
 5. A conveyor system according to claim 4, wherein theworkstation locking mechanism first locks the pallet in position priorto releasing engagement with the moving element and allows engagement ofthe moving element prior to releasing the pallet.
 6. A conveyor systemaccording to claim 1, wherein the moving elements are supported on thetrack section by an upper runner and a lower runner and the upper runneris angled to provide pressure holding the moving elements between theupper runner and the lower runner,
 7. A conveyor system according toclaim 2, wherein the workstations comprise workstations with multiplepallet locations to operate on more than one pallet at a time in orderto adjust for differing cycle times.
 8. A conveyor system according toclaim 1, wherein the control system comprises a moving element trackingsystem comprising: an encoder strip provided to the moving element; aplurality of encoder read heads provided to the track section andconfigured to read the encoder strip as moving elements move past thelocation of the encoder read heads.
 9. A conveyor system according toclaim 8, wherein the encoder strip comprises a plurality of index pointsstaggered along the strip.
 10. A conveyor system comprising: an infeedstation comprising: a singulator provided to hold pallets received froman infeed conveyor and release them from the infeed section; a tracksection in communication with the infeed station, the track sectioncomprising: a plurality of moving elements configured to engage withpallets from the infeed section; a track; a workstation; a controlsystem configured to independently control the moving elements formovement along the track to and from the workstation; an outfeed stationconfigured to receive pallets from the track section and feed thepallets to an outfeed conveyor, which is in communication with the tracksection, for additional processing.
 11. A conveyor system according toclaim 10, wherein the track comprises a magnetic drive system.
 12. Aconveyor system according to claim 10, wherein the moving elementsengage and disengage with the pallets via an engagement systemcomprising: a moving element portion that is biased to be engaged butcan be disengaged at a workstation; a workstation portion provided atthe workstation and configured such that, when the moving element entersthe workstation the workstation element disengages the moving elementfrom the pallet.
 13. A conveyor system according to claim 11, whereinthe moving element portion comprises: a frame provided to the movingelement; a movable pin provided to the frame that is biased toward theengagement position, and the workstation portion comprises: a movablemechanism provided at the workstation that, when advanced, is configuredto operate against the bias to retract the movable pin for disengagementwith the pallet, and, when retracted, allows the movable pin to engagewith the pallet.
 14. A conveyor system according to claim 13, whereinthe workstation further comprises: a workstation locking mechanism that,when activated, locks the pallet in position at the workstation, whereinthe workstation locking mechanism is configured to operate with themovable mechanism such that the pallet is engaged with either of theworkstation or the moving element at all times.